Parallel plate capacitor.
At the most basic level every application of Newton's Laws is governed by action-at-a-distance forces, fundamental forces. The comparison and contrast of the electromagnetic and gravitational forces is a major theme in this course. As the course progresses, we will also occasionally mention the flip-side of electrostatic force in these discussions, the magnetic force. At this stage, though, when we mention magnetism, this is mainly to create an expectation, or a sense, of its importance. For now, let us focus on gravitation versus electricity.
As with gravitation, an electrostatic system might produce an environment where the force on a particle is the same everywhere, or, conversely, the force might change at different points within the system. A commonly discussed constant force environment for electrostatic force exists in the space between the plates of a parallel plate capacitor, a frequent MCAT motif.
Between the plates of the capacitor, charged particles move similarly to projectile motion. Start looking for these constant field systems in your problem solving and practice MCATs and start thinking about it: gravity near the earth's surface and the electric field between parallel plates.
This is something we will often do in these discussions, preview later material in the context of a current concepts. Here, in mechanics, we are talking about Newton's Laws, which govern basic force interaction. An important theme are the fundamental forces, and so I am taking an opportunity to point some of the simple model systems used for teaching and problem solving, i.e. the constant field environments for gravitation and electrostatics.
We are staking a claim to begin a theme of development. As we return again and again to the most important concepts, each repetition reconfirms the importance and builds familiarity into knowledge.